Electrochemical characterization of vanadium(V) sensors modified with 2,4-dinitrophenyl hydrazine. Studying the reaction mechanism using SEM and IR

The determination of vanadium(V) ion in different environmental water samples using rapid, sensitive, and selective potentiometric ion selective electrodes; Screen printed (SPE) and carbon paste (CPE) electrodes modified with 2.4-dinitrophenyl hydrazine (DNPH) was described. Effect of various plasticizers (o-NPOE, TCP, DBP, DOS and DOP) and ionophore content were studied. The best performance was obtained with the electrodes plasticized with o-NPOE or TCP. The electrodes were characterized with scanning electron microscope (SEM) and energy dispersive X ray analysis (EDX) and the mechanism of the electrodes response is discussed based on IR spectra measurement. The sensors exhibit good selectivity toward vanadium(V) ions over a concentration range from 1.0 × 10− 6 to 1.0 × 10− 2 mol L− 1 with a lower detection limit of 1.0 × 10− 6 mol L− 1 and a Nernstian slope of 12, 11 and 10.5 mV decade− 1 for SPE (electrode I) and CPEs (electrodes II and III using o-NPOE and TCP plasticizers, respectively). The sensors show response time of 15, 20 and 30 s over the linear concentration range for electrodes I, II and III, respectively. The potentiometric response is independent on the pH of the solution in the pH range 5.0-8.0. They display satisfactorily good discrimination toward vanadium(V) ions with regard to most common transition metal ions. The sensors are applied for determination of V(V) ions in different spiked water samples (tap and waste water) with satisfactory results. The method was validated with regard to IUPAC recommendation parameters.